The present invention relates to machines for manufacturing coiled springs, and in particular, to the tool for establishing the spacing between adjacent coils.
The automatic fabrication of springs from a roll of wire, has been practiced for many years, as evidenced by U.S. Pat. No. 2,119,002 issued May 31, 1938 for "Spring Coiling Machine". Some of the basic operating techniques are also disclosed, for example, in U.S. Pat. No. 5,131,251 issued Jul. 21, 1992 for "Chuck Set Up For Spring Coiling Machine", and U.S. Pat. No. 5,201,208 issued Apr. 13, 1993 for "Coiling Point Holder For Spring Coiling Machine", the disclosures of which are hereby incorporated by reference.
FIGS. 1 and 2 illustrate some of such known techniques. The spring coiling machine 10 may be any of numerous makes and models which are employed for manufacturing coil springs in an automatic, highly efficient process. For ease of consistent reference to directionality, FIGS. 1 and 2 include the orthogonal axes indicated with the positive and mutually perpendicular X, Y and Z axes.
The spring coiling machine 10 employs a multiplicity of gears, linkages, levers, cams and power supplies, all of which are operatively integrated for the purposes of feeding, bending, and cutting a wire W at a coiling station 20. Most of these mechanisms are situated behind the front panel 30. The wire W is plastically deformed at the coiling station into a coil spring S having desired characteristics such as diameter, length and pitch which may vary for a given coil. The coil spring S is then severed from the supply wire. The manufacturing sequence is continuously replicated so that multiple coil springs are produced without any interruption in a highly efficient manufacturing process.
The coiling station 20 operates on the workpiece in the form of a continuous wire to produce the coil spring S. The supply of wire W is displaced by feed rolls 24 through a wire guide 26 and a block wire guide 28. The wire is continuously displaced generally parallel to the front face of panel 30 of the machine until it reaches the arbor 32. The front panel 30 of the machine extends outwardly from the plane of FIG. 2 toward the operator. The arbor 32 and the block wire guide 28 are mounted to a tool holder or chuck 40 which is mounted through the front panel 30 and clamped into position. A coiling point 34 contacts the wire as it emerges from between the arbor 32 and the block guide 28 and deformably forces the wire into a generally helical shape. A pitch tool 36 is conventionally wedged at an angle to the wire thereby establishing the pitch of a plurality of successive loops or turns in the coil. When the spring reaches the desired number of turns, a cutting tool 50, for example in the form of a tension assembly having a projecting cutting blade 52, is actuated. The blade 52 is pivotally displaced from the upper left in the direction indicated as a counterclockwise arrow in FIG. 1, to sever the feed wire against the arbor 32 and thereby complete the fabrication of the coil spring S.
In conventional spring coiling machines, it is common to have a plurality of wire rolls 54, 54', 54" each having a wire with a different diameter, shape and/or composition so that for a given work order, a specific supply of wire can be selected and supplied to the coiling station 20. The feed paths from the wire rolls typically extend through generally parallel wire guide channels 60, 60', 60" which are spaced in the Z direction from the front panel 30 of the machine adjacent the coiling station. The wire selected for a given work order, is then fed from the specific wire guide 60, 60', 60" to the block wire guide 28 for deformation to produce the coil spring. Because the feed locations of the various wire guides and paths have different input positions to the coiling station 20 according to the selected wire, it is necessary to specifically axially align the block wire guide 28 with the wire guide for the given selected wire supply. For example, as illustrated in FIG. 2, the block wire guide 28 can be repositioned in the Z direction to align the block wire guide 28 with guide channel 60' or 60". The cutter 50, pitch tool 36, and coiling point 34 must also be adjustable.
An important component of the total cost of manufacture for an order of a particular type of spring, is the combination of machine down time and operator labor, associated with making such adjustments in setting up the machine to perform the particular operations by which the desired spring is fabricated, and maintaining the effectiveness of these operations, e.g., by the periodic sharpening or replacement of worn tools.
The spacing of the coils in a spring is controlled by the pitch mechanism, which is actuated from behind the front panel 30. The pitch mechanism in one type of conventional machine, is shown in FIG. 3. As the pitch cams 62 on the cam shaft 64 rotate, motion is transmitted to the compound lever 66 through the cam roll lever 68 and compound lever block 70. One end of the cam roll lever 68 is attached to tie rod 86, and one end of the compound lever is attached to the compound lever shaft 72. The pull rod 74 (which is attached to the compound lever) moves up and down with the rocking action of the lever. When the pull rod moves downward, the pitch bell crank 76 pivots causing the pitch tool 36 to move outward from the chuck 40, thus increasing the pitch or distance between coils in the spring being coiled. The pitch tool 36 is attached to drive block 84 via screw 90. The return springs 78 pull the bell crank 76 back when the low portion of the pitch cams 62 roll over the cam roll 80. The pitch stop screw 82 limits the travel of the bell crank 76. While the bell crank is against the stop screw, movement of the pitch tool is stopped and the coils formed in the spring are of a fixed pitch. By turning the pull rod adjusting knob 88 counterclockwise, the cams become inoperative and the spacing of the spring coils become dependent upon the position of the stop screw 82.
Other types of spring coiling machines have different pitch mechanisms, but in all instances, a pre-established control program specifies the movement of the pitch tool 36 toward and away from the face of chuck 40, in relation to the extent of wire that has been fed to the coiling point, such that a non-uniform pitch can be provided between the coils of the completed spring. Such non-uniform pitch can be provided on the one hand, in a spring having coils of uniform diameter, or on the other hand, in a spring where the coil diameters are also non-uniform. Pitch control can be accomplished not only with cam mechanisms of the type shown in FIG. 3, but also with computer controlled mechanisms for achieving the desired program of positioning the tool 36 relative to the front face of the chuck 40.
Regardless of the type of pitch mechanism employed on a particular machine, considerable time is required for initial set up and adjustment, and for the periodic replacement of a worn tool. With reference to FIG. 3, replacement of a pitch tool 36 in the drive block 84 can be simply accomplished by loosening screw 90, removing the old tool, replacing it with a new tool, and tightening the screw 90. This replacement procedure does not necessarily mean that the neutral position and motion of the new pitch tool will duplicate that of the replaced pitch tool.